Refrigerating device comprising an evacuatable storage compartment

ABSTRACT

A refrigerating device including a hollow-walled housing surrounding a first and a second storage compartment. A vacuum pump is controlably connected via a suction line to the hollow chamber of the housing and to one of the storage compartments. The pump is controlled to maintain a desired pressure range in both the housing and the storage compartment.

The invention relates to a refrigerating device comprising ahollow-walled housing surrounding a storage compartment and comprising avacuum pump which is connected to a hollow chamber of the housing via asuction line.

It is known that the storage of readily perishable foodstuffs undervacuum improves their keeping quality. Thus, for example, a refrigeratoris disclosed in WO 01/712 63 A1 in which a storage compartment isprovided to hold readily perishable foodstuffs. The storage compartmentcan be evacuated in order to improve the keeping quality of thefoodstuffs. In order to achieve a vacuum inside the storage compartment,a pumping device is provided for the storage compartment. In this case,the pumping device is integrated into the refrigerator and takes up aconsiderable fraction of the refrigerator volume at the expense ofstorage space in the refrigerator.

It is also known to manufacture refrigerating devices with hollow-walledhousings which can be evacuated since such housings considerably improvethe thermal insulation of the refrigerator interior. A distinction ismade here between hermetically sealed systems and actively pumpedsystems. In the hermetically sealed systems the vacuum is maintainedinside the hollow-walled housing after a single evacuation process forthe lifetime of the refrigerator. These include vacuum insulation panelsand hermetically sealed complete housings. As a result of the extremerequirements with regard to vacuum tightness, however, these systems areexpensive to manufacture and very costly. Thus, for example, the highvacuum requirements can only be ensured by a stainless steel jacket.Actively pumped systems on the other hand use substantially cheaperplastic housings which are easier to process, which can be filled with asupporting body material which can be correspondingly evacuated.However, in these systems a pump fixedly connected to the housing or anabsorption system is required to maintain the vacuum.

The object of the present invention is to provide an inexpensiverefrigerating device with which readily perishable foodstuffs can bepreserved over a fairly long time.

The object is solved by a refrigerating device having the features ofthe preamble of claim 1 in which the suction line is further connectedto the storage compartment.

The refrigerating device according to the invention combines theadvantages of an evacuatable storage compartment with the advantages ofan actively pumped refrigerating device. Since according to theinvention, the same vacuum pump is responsible for generating a vacuumboth in the hollow-walled housing and in the storage compartment, asecond vacuum pump can be dispensed with. As a result, the manufacturingcosts for the refrigerating device and also its operating costs arereduced because only one vacuum pump which is an energy consumer isprovided. Finally, as a result of using only one pump, less space isrequired so that larger storage space capacities are available in theinterior of the refrigerating device.

In the refrigerating device according to the invention the housing cansurround an interior space in which the storage compartment and anon-evacuatable storage chamber are located. Thus, in the samerefrigerating device less-readily perishable foodstuffs can be storedtogether with the readily perishable foodstuffs which are stored in theevacuated storage compartment without it being necessary to destroy thevacuum in the storage compartment during their removal from therefrigerating device.

Advantageously the refrigerating device has a control circuit forcontrolling the pump using at least one pressure sensor arranged on thesuction side of the pump. Using such a pressure sensor it can beidentified when the pressure in the hollow-walled housing or in thestorage compartment exceeds a certain value in order to cause the pumpto extract the excess pressure in such a case. In this way,power-consuming unnecessary permanent operation of the pump is avoidedsince this is only put into operation when there is a need to maintain arequired underpressure.

In this case, the refrigerating device advantageously has a switchingvalve in the suction line for selectively connecting the pump to thehollow chamber or to the storage compartment. Thus, as required thepumping action of the pump can be switched over between the hollowchamber and the storage compartment by the control circuit.

In this case, the control circuit controls the position of the valveusing at least one pressure sensor.

The control circuit can be connected to a sensor to record theevacuatability of the storage compartment. The storage compartment canthen be evacuated if it is hermetically sealed with respect to theenvironment, i.e., if a door for removal or for insertion of thefoodstuffs is closed. With such a sensor, operation of the pump when thedoor is open and associated severe loading of the pump can be avoided.

The control circuit advantageously controls the switching valve toconnect the storage compartment to the pump when the evacuatabilitysensor records the evacuatability of the storage compartment. Asmentioned above, the evacuatability of the storage compartment isprovided when the door of the storage compartment is closed so that thepump can bring about a reduction in pressure inside the storagecompartment when the door is closed.

In one embodiment the evacuatability sensor is arranged on a door of thestorage compartment to record the opening and closing state of the door.

In a further embodiment, the evacuatability sensor is a pressure sensorand the valve has a switching position in which it has a high admittancebetween storage compartment and pump and one switching position with asmall non-vanishing conductance between storage compartment and pump.If, in such an embodiment, the evacuatable storage compartment isflooded in order to be able to open its door, the control circuitimmediately switches the switching valve into the switching positionwith the low admittance. If the pump is now put into operation, possiblybecause the pressure sensor is arranged on the evacuatable compartmentand records an excessively high pressure, only a small air flow is nowextracted from the evacuatable compartment. As long as the door is open,the pressure inside the storage compartment does not drop but remains ata constant value corresponding to the external ambient pressure, whichis also detected by the pressure sensor. A lack of a pressure drop isthe signal for the control circuit that the door of the storagecompartment is open. A pressure drop which is recorded by the sensoronly occurs when the door of the storage compartment is closed again.Only when the sensor thus indicates the evacuatability of the storagecompartment does the control circuit switch the switching valve into theposition with the high admittance and the storage compartment isspeedily evacuated.

The hollow chamber of the housing advantageously has a loose filling ofa supporting material. The supporting material imparts an increasedstability to the hollow-walled housing.

In this case, the supporting material is preferably porous. Such asupporting material contributes to the thermal insulation of theinterior of the refrigerating device.

The supporting material is especially preferably a silicic-acid oraerogel-based granular material.

The pump is advantageously a rough-vacuum pump. A rough vacuum isunderstood as a pressure of about 100 mbar. Rough-vacuum pumps are morerobust and less expensive compared to high-vacuum pumps. Especially ifthe hollow cavity of the housing is filled with a supporting material, arough vacuum of about 100 mbar is already sufficient to bring about asignificant improvement in the insulation of the interior of therefrigerating device compared with a non-evacuated state of the hollowchamber of the housing of the refrigerating device.

The storage compartment an/or the hollow chamber especially preferablyhave plastic walls. An important advantage of plastic walls is theircheapness and ease of processing.

The invention is explained in detail in the following with reference totwo exemplary embodiments. In the figures:

FIG. 1 is a cross-section through a refrigerator according to theinvention; and

FIG. 2 is a cross-section through a further refrigerator according tothe invention.

FIG. 1 shows a cross-section through a refrigerator 1 as an example fora refrigerating device according to the invention. The refrigerator 1has a rectangular external shape and is surrounded by a hollow-walledhousing 2 with the exception of one front side. In this case, thehollow-walled housing 2 is filled with a porous supporting material 5which comprises a silicic-acid or aerogel-based granular material.Provided at the front of the refrigerator 1 is a hinged front door 3with a handle 4 in order to obtain access via this to an interior spaceof the refrigerator 1.

The interior of the refrigerator 1 is divided into an upper storagechamber 6, a lower storage chamber 7, an operating region 8 arrangednext to the lower storage chamber 7 and a region occupied by anevacuatable storage compartment 9. In this case, the upper storagechamber 6 is separated from the lower storage chamber 7 and theoperating region 8 by the storage compartment 9. Horizontally aligneddepositing surfaces or depositing grids 10 are provided in the upperstorage chamber 6 and in the lower storage chamber 7. The storagecompartment 9 has a flap 11 on the front side via which the food can beplaced in the storage compartment 9 or removed therefrom. In theevacuated state the flap 11 is pressed against the housing of thestorage compartment 9 by the ambient pressure such that it ishermetically sealed. A flooding valve 21 is provided on the housing ofthe storage compartment 9.

A compressor 12, a pump 13, a valve 15 and a control unit 18 areprovided in the operating region 8. A vaporiser and condenser whichtogether with the compressor 12 form a coolant circuit are not shown forthe sake of clarity. The pump 13 is a rough-vacuum pump which is set toa target pressure of 100 mbar. It is connected via a suction line 14 tothe inner hollow chamber of the housing 2 and to the evacuatable storagecompartment 9. Arranged on a fork of the suction line 14 is a switchingvalve 15 which is designed to take on a plurality of switching positionsunder the control of the control unit 18. It has respectively oneswitching position in which it connects the pump 13 to the storagecompartment 9 or the hollow chamber of the housing 2 with a highadmittance and one switching position in which it connects the pump 13to the storage compartment 9 with a low admittance. The control unit 18further serves to control the pump 13. For this purpose it is connectedvia control lines 20 to the pump 13 and the valve 15. It is furthermoreconnected by means of a data line 22 to the flooding valve 21 and bymeans of data lines 19 to two pressure sensors 16 and 17 wherein thesensor 16 is arranged in the interior of the storage compartment 9 andthe sensor 17 is arranged in the hollow chamber of the hollow-walledhousing 2. The pressure sensors 16, 17 each detect a pressure inside thestorage compartment 9 or in the hollow chamber of the hollow-walledhousing 2 and transmit the result of their measurement via the datalines 19 to the control unit 18.

During operation of the refrigerator 1 the pressure in the interior ofthe storage compartment 9 and in the interior of the hollow-walledhousing 2 is constantly measured by the pressure sensors 16 and 17 andthe result of the measurement is passed onto the control unit 18. Inthis case, a maximum upper limit which must not be exceeded, ispre-determined both for the pressure in the interior of the storagecompartment 9 and also for the pressure in the interior of the housing2. If one of the two sensors 16 or 17 detects that the pressuremonitored by it exceeds this limit, the control unit 18 responds bycontrolling the valve 15 and switching the valve 15 such that the pump13 is connected via the suction line 14 to the storage compartment 9 orto the hollow chamber of the housing 2 depending on in which of the twothe exceeding of the limit for the pressure was detected by thecorresponding sensor 16, 17. In addition, the control unit 18 sets thepump 13 in operation so that the excess pressure is extracted and thetotal pressure in the storage compartment 9 or the housing 2 falls belowthe pre-determined limit again. As soon as the corresponding sensor 16or 17 detects a pressure which has a pre-determined difference from theupper limit for the pressure, the control unit 18 switches the pump 13off again. In this way, it is ensured that the pump 13 only operateswhen it is required to extract an excess pressure whereby unnecessaryenergy consumption is avoided.

The flap 11 must be opened to remove or deposit food from or into thestorage compartment 9. For this purpose, the interior of the storagecompartment 9 must be flooded. For this purpose, the flooding valve 21is provided which is actuated manually and closes as soon as it isreleased by the user. In addition, the flap 11 is designed so that itbursts open after the pressure has been equalised. If a user opens theflooding valve 21 and air flows into the storage compartment 9, thepressure sensor 16 registers a pressure rise which causes the controlunit 18 to switch on the pump 13. At the same time, the control unit 18receives a signal via the data line 22 which indicates that the floodingvalve 21 is open. The control unit 18 responds to this by bringing theswitching valve 15 into the switching position in which it connects thepump 13 and the storage compartment 9 with low admittance. Whilst thestorage compartment is open, the pump 13 continuously extracts a small,non-vanishing air flow from the storage compartment 9.

In order to hermetically seal the storage compartment 11 again, the flap11 is pressed shut when the flooding valve 21 is released. As soon asthe flap 11 is closed, the small air flow extracted from the storagecompartment 9 by the pump 13 is sufficient to slightly reduce thepressure inside the storage compartment 9. The pressure reduction isrecorded by the pressure sensor 16 and is the signal for the controlunit 18 that the flap 11 was closed. Via the control line 20 saidcontrol unit therefore controls the valve 15 to connect the pump 13 withhigh admittance to the storage compartment 9 so that the pump 13 fromnow on rapidly reduces the pressure inside the storage compartment 9. Ifthis pressure goes below a lower pre-determined value, the pump 13 isswitched off again by the control unit 18. Only when the sensors 16 or17 register that the pressures monitored by them in the storagecompartment 9 or in the hollow chamber of the housing 2 exceed one ofthe pre-determined limits, is the pump 13 started up again by thecontrol unit 18 and connected via the valve 15 as required either to thestorage compartment 9 or to the hollow chamber of the hollow-walledhousing 2.

In the further embodiment of the refrigerator 1 according to theinvention shown in cross-section in FIG. 2, the storage compartment 9has no flooding valve unlike the embodiment shown in FIG. 1. A furtherdifference from the embodiment shown in FIG. 1 is that the refrigeratorshown in FIG. 2 is only fitted with one pressure sensor 16 which isarranged in the suction pipe 14 between the pump 13 and the valve 15 andis connected via the data line 19 to the control unit 18. Furthermore adoor sensor 24 is also provided on the flap 11 which is also connectedto the control unit 18 via the data line 22. The valve 15 has a fourthconnection at which a ventilation line 23 open to the surroundings ofthe refrigerator discharges. The valve 15 can be switched between threeswitching positions: in a first switching position the ventilation line23 is connected to the interior of the storage compartment 9 via thesuction line 14 whereas the branch of the suction line 14 leading to thehollow chamber of the housing 2 is shut off; in a second switchingposition the ventilation line 23 and the branch of the suction line 14leading to the hollow chamber of the housing 2 are shut off whereas thepump 13 is connected to the storage compartment via the valve 15, and ina third switching position the ventilation line 23 and the branch of thesuction line 14 leading to the storage compartment 9 are shut off.

During normal operation of the refrigerator 1 the valve is in the thirdswitching stage so that the pump 13 is connected to the hollow chamberof the housing 2 via the suction line 14. In this case, the samepressure prevails in the suction line 14 as in the hollow chamber. Thisis measured by the sensor 16 and communicated via the data line 19 tothe control unit 18. As in the embodiment in FIG. 1, a limit for thepressure is defined for the control unit wherein, if this limit isexceeded by the pressure, the control unit 18 causes the pump 13 to pumpaway any excess pressure. As soon as the pressure lies below apre-determined pressure again, the pump 13 is switched off by thecontrol unit 18.

To open the flap 11 of the storage compartment 9 the control unit 18 ismade to switch the valve 15 to the first switching stage by means of amanual switch not shown. As a result, the interior of the storagecompartment 9 is flooded with ambient air via the suction line 14 andthe ventilation line 23 until pressure equalisation has beenestablished. The flap 11 is then opened or it bursts open when thepressure is equalised.

In order to hermetically seal the storage compartment 9 again, the flap11 is pressed to. In this case, the door sensor 24 registers the closedstate (for example, by means of the presence of an electrical contact oran interruption of an electrical contact) and passes this information onto the control unit 18 via the data line 22. This causes the valve 15 toswitch to the second switching stage so that the pump 14 is connected tothe interior of the storage compartment 9 via the suction line 14 whilstthe ventilation line 23 is shut off and the hollow chamber of thehousing 2 is separated from the pump 13. Now the pump 13 can pump outthe storage compartment 9. The pressure sensor 16 again registers theprevailing pressure and transmits its measurement result to the controlunit 18. As soon as the pressure falls below a pre-determined value, thevalve 15 is again switched to the third switching stage by the controlunit 18 and the pump 13 is switched off. The refrigerator 1 immediatelytakes up its normal operation.

1-14. (canceled)
 15. A refrigerating device, comprising: at least onestorage compartment; a hollow-walled housing forming a hollow chambertherein surrounding said storage compartment; and a vacuum pumpconnected via a suction line to both said storage compartment and saidhollow chamber.
 16. The refrigerating device according to claim 15,including a non-evacatuable storage chamber and said hollow-walledhousing forming an interior space in which said storage compartment andsaid a non-evacuatable storage chamber are located.
 17. Therefrigerating device according to claim 15, at least one pressure sensorarranged on the suction side of said pump and a control circuit coupledto said pressure sensor for controlling said pump.
 18. The refrigeratingdevice according to claim 17, including a switching valve coupled tosaid suction line for selective connection of said pump to at least oneof said storage compartment and said hollow chamber.
 19. Therefrigerating device according to claim 18, including said controlcircuit controlling said selective connection of said switching valve inresponse to said pressure sensor.
 20. The refrigerating device accordingto claim 19, including a sensor coupled to said control circuit forrecording the evacuatability of said storage compartment.
 21. Therefrigerating device according to claim 20, including said controlcircuit controlling said selective connection of said switching valve inorder to connect said storage compartment to said pump when saidevacuatability sensor records a predetermined evacuatability of saidstorage compartment.
 22. The refrigerating device according to claim 20,including said storage compartment having a door and said evacuatabilitysensor coupled to said door to record the opening and closing state ofsaid door.
 23. The refrigerating device according to claim 20, includingsaid evacuatability sensor is a pressure sensor and said switching valvehas a first switching connection in which said switching valve forms ahigh admittance between said storage compartment and said pump and has asecond switching connection in which said switching valve forms anon-vanishing low admittance between said storage compartment and saidpump.
 24. The refrigerating device according to claim 15, including saidhollow chamber contains a loose filling of a support material.
 25. Therefrigerating device according to claim 24, including said supportmaterial is a porous material.
 26. The refrigerating device according toclaim 25, including said support material is at least one of a silicicacid or an aerogel-based granular material.
 27. The refrigerating deviceaccording to claim 15, including said pump is a rough vacuum pump. 28.The refrigerating device according to claim 15, including at least oneof said storage chamber and said hollow-walled housing have walls madeof a plastic material.
 29. A refrigerating device, comprising: at leastone storage compartment; at least one non-evacatuable storage chamber; ahollow-walled housing forming a hollow chamber therein and forming aninterior space surrounding said storage compartment a non-evacatuablestorage chamber; a vacuum pump connected via a suction line to both saidstorage compartment and said hollow chamber; a switching valve coupledto said suction line for selective connection of said pump to at leastone of said storage compartment and said hollow chamber; at least onepressure sensor arranged on the suction side of said pump; and a controlcircuit coupled to said pressure sensor for controlling said pump, saidcontrol circuit controlling said selective connection of said switchingvalve in response to said pressure sensor.
 30. The refrigerating deviceaccording to claim 29, including a sensor coupled to said controlcircuit for recording the evacuatability of said storage compartment andsaid control circuit controlling said selective connection of saidswitching valve in order to connect said storage compartment to saidpump when said evacuatability sensor records a predeterminedevacuatability of said storage compartment.
 31. The refrigerating deviceaccording to claim 30, including said storage compartment having a doorand said evacuatability sensor coupled to said door to record theopening and closing state of said door.
 32. The refrigerating deviceaccording to claim 30, including said evacuatability sensor is apressure sensor and said switching valve has a first switchingconnection in which said switching valve forms a high admittance betweensaid storage compartment and said pump and has a second switchingconnection in which said switching valve forms a non-vanishing lowadmittance between said storage compartment and said pump.
 33. Therefrigerating device according to claim 29, including said storagechamber and said hollow-walled housing have walls made of a plasticmaterial said hollow chamber contains a loose filling of a poroussupport material.